Merritt targets mosquito larvae from above
Hovering in a helicopter high above the city, you can see a river snaking its way along the land and the reflective surface of water pooling in fields.
These liquid features of the landscape, barely visible from the ground below, are potential breeding grounds for nuisance mosquitoes and the target of the City of Merritt’s mosquito control program.
Efforts to mitigate mosquito populations within the City began in April and will continue until the end of August, said registered biologist Damian Regan, whose company D.G. Regan and Associates has been hired to kill mosquito larvae that hatch in standing water and flood pools.
The City dedicated nearly $63,000 to mosquito control this year.
“Residents might see our helicopters flying with a bucket underneath,” said Regan. “We’re there on an ongoing basis throughout the season.”
The company uses a naturally occurring control agent called VectoBac that has no effect on the environment other than to kill mosquito larvae by dropping pellets into the water.
“VectoBac in a non-chemical, organic agent that selectively targets the mosquito larvae,” said biologist Terry Bach at the Merritt airport on Thursday, while waiting for local helicopter pilot John Graham to return from an aerial application.
Because water levels change and the natural agent doesn’t accumulate, crews have to reapply it throughout the summer as new mosquito larvae hatch.
Mosquito populations typically increase as water levels rise and flooding occurs, because mosquito eggs need water to hatch.
“We have an extensive database of larval habitats and when they become active,” said Regan. “We try to coincide the treatments at the most opportune times.”
Treatments include aerial applications piloted by Graham of Graham Helicopters, as well as ground applications. Bach said biologists can test pools accessible by foot for larvae and throw the pellets in by hand.
While the program is effective in reducing mosquito populations, both Regan and Bach said residents will still notice some adult mosquitoes.
“There are always places that produce mosquitoes that we don’t know about,” said Regan. “And any year, depending on the area, we can have adult mosquitoes blow into the city.”
Merritt winds, combined with the fact that mosquitoes can travel up to several kilometres, mean mosquitoes can still enter the city from beyond the control program boundaries, he said.
“We do expect that in a week or two there could be a blossom of adult mosquito activity,” said Regan. “There’s a lot of science to the control program, but ultimately Mother Nature is in control.”
Residents can assist in the control efforts by draining standing water on properties — everything from old tires to buckets. And, to avoid mosquito bites, Regan said residents should avoid going outside between dusk and dawn, avoid dark clothing and use DEET.